View Source ExTDLib.Object.ChatEventVideoChatParticipantVolumeLevelChanged (ExTDLib v0.0.4)

A video chat participant volume level was changed.

Name	Type	Description
participant_id	MessageSender	Identifier of the affected group call participant.
volume_level	number	New value of volume_level; 1-20000 in hundreds of percents.

More details on telegram's documentation.